1. Field of the Invention
The present invention relates to a quad flat flip package and a leadframe thereof. More particularly, the present invention relates to a quad flat flip package and a leadframe for the quad flat flip package, which helps prevent bump-collapse.
2. Description of the Related Art
Semiconductor Industry is one of the most developed technology in recent years. With the technology advancing, the hi-tech electronics industries have developed thinner, lighter and more compact products with artificial intelligence and better functions. In the manufacturing process of semiconductor products, a leadframe is one of the most common elements in package. A quad flat package (QFP) can be divided as I-type (QFI), J-type (QFJ) and non-lead-type (QFN), according to the shape of the lead of leadframes. Since the QFP has relatively shorter signal traces and a faster speed for signal transmission, it has become the mainstream for the package with low pin count, and is suitable for the chip package with high-frequency (i.e. radio frequency) transmission.
FIG. 1 is a side view of a conventional quad flat non-lead flip chip package. FIG. 2 is a bottom view of the conventional quad flat non-lead flip chip package of FIG. 1.
Please refer to FIGS. 1 and 2. The conventional quad flat non-lead flip chip package 100 comprises a chip 110, a leadframe 120 and a molding compound material 130. The chip 110 has an active surface 112 and a corresponding backside surface 114. The active surface 112 refers to a surface having active elements. Further, bonding pads 116 are located on the active surface 112 of the chip 110. The bonding pads 116 are usually exposed through openings of a passivation layer (not shown).
The leadframe 120 includes a plurality of leads 122, and each of the leads 122 has a top surface 122a and a bottom surface 122b. The bonding pads 116 of the chip 110 are respectively connected with the top surface 122a of the leads 122 through bumps 140, such that the bonding pads 116 are electrically connected with the leads 122. The molding compound material 130 encapsulates the chip 110, bumps 140 and leads 122 and exposes the bottom surface 122b of each of the leads 122, as shown in FIG. 2.
Back to FIG. 1, in the conventional manufacturing process of a quad flat non-lead package, the bumps 140 connected with the bonding pads 116 are made of soft metal with a low melting point such as Sn63/Pb37 alloy. During a reflow process, since it is hard to control the wetting extent of the low-melting-point solder and sometimes the melted solder extends too far (i.e. wetting extent too larger), the bumps 140 may collapse. In order to solve this problem, it is known to use high lead bumps whose melting temperature is relatively high to replace the eutectic bump mentioned above. Because of the bondability between the top surface 122a of the leads 122 and the high lead bumps is poor, a solder paste 150 is required to be sprayed on the top surface 122a of the leads 122. However, the high lead bumps are more expensive, thus increasing the manufacturing costs. Also, because a solder paste is required for the high lead bumps, the manufacturing processes become more complicated.